> I suspect that only a minority of people in metric-using countries -- those with basic chemistry knowledge fresh in their mind -- know that "one milliliter of water occupies one cubic centimeter, weighs one gram, and requires one calorie of energy to heat up by one degree centigrade".
They taught us that in 4th grade in cooking classes. Then they made us remember that in physics and chemistry classes 2 years later.
The point is that this particular concept of metric units is taught really well (repeatedly on many practical examples and then evwn theoretical ones) and so virtually everyone knows and uses it. It's deeply ingrained in cooking books, recipes, etc.
Of course I don't remember a lot of things from the 4th grade. This one stands out.
They taught us that in 4th grade in cooking classes. Then they made us remember that in physics and chemistry classes 2 years later.